Environmental Science and Engineering Seminar

Laure Zanna, Associate Professor of Climate Physics, Department of Physics, University of Oxford

The ocean absorbs a significant portion of the anthropogenic heat released in the climate system, leading to an increase in global mean sea level rise. The patterns and rate of ocean heat uptake are governed by several processes such as air-sea interaction, and deep water formation. However, heat redistribution via changes in ocean circulation further impacts the spatial patterns of heat storage induced by natural variability and anthropogenic forcing.

Using a combination of observations, theory, and models, we attribute about half of the thermosteric sea level change, in the past 50 years at 40N, to ocean circulation changes - likely induced by air-sea variability. We further explore the link between air-sea fluxes, ocean circulation changes, and heat uptake in future projections. Our findings highlight high-latitude forcing as the leading cause of regional sea level projection uncertainty, over the parametrization of ocean processes. We propose ways forward to constrain regional projections of ocean heat uptake and sea level rise, including the use of anthropogenic carbon.